Angioplasty balloon catheter and adaptor

ABSTRACT

The invention described is a single lumen balloon catheter with a detachable adaptor, a rotatable guide wire and a short guide tube, in which the guide tube provides a path for the guide wire, the adaptor incorporates means for rotating the guide wire and whereby axial force can be transmitted to the guide tube. In one embodiment, a resilient spring member couples the main catheter body to the guide tube for transmitting axial force therebetween, while permitting fluid communication between the inflation lumen and the balloon.

This is a continuation of application Ser. No. 07/743,189, filed Aug. 9,1991 now U.S. Pat. No. 5,318,529.

BACKGROUND OF THE INVENTION

Angioplasty balloon catheters are well known in the art. Basically theyare comprised of a balloon portion and a catheter tube portion, theballoon portion being mounted on or attached to the catheter tubeportion at or adjacent the distal end thereof. In use, the balloonportion is advanced through an artery, often over a guide wire which hadpreviously been passed through the artery. The advancement is continueduntil the balloon is within a stenosis. It is then expanded byapplication of fluid pressure through the catheter tube.

Angioplasty catheters are normally of relatively small diameter and arepreferably very flexible or "soft" to facilitate negotiating often verytortuous arterial paths. The balloon is advanced through the arterialtree by pushing on the catheter tube.

Sometimes, during the advancement of the balloon through the artery, itmay encounter a lesion which impedes passage. In such a case, furtherforce applied to the catheter, instead of producing further advancementof the balloon, merely causes the tube and/or the balloon, to crinkle,or collapse, or double up on itself within the artery. Most, often, theobstruction which leads to this is the very lesion causing the stenosiswhich the balloon is intended to expand.

Indwelling, or in situ guide wires have been used to try and overcomethis difficulty. Because they are much thinner than the catheters andsince they tend to be stiffer, they can often be guided through thesmall lumen of a stenotic region which a catheter alone might not beable to negotiate. With the guide wire having traversed the area of thelesion, a catheter passing over that wire can then find and negotiatethat same path much more easily than if the guide wire were not there.Such guide wires also help the catheters passing over them to resistbuckling as they pass through severely narrowed sections of the artery.Nevertheless, they have been only partially successful in amelioratingthe tendency of the very flexible catheter tube to collapse, buckle orfold upon itself. That is because the axial force necessary to advancethe balloon is still transmitted through the soft, flexible cathetertube. In addition, the need to pass over an indwelling guide wireimposes a minimum size limitation upon the diameter of the catheter tubeand, as a result, on the collapsed profile of the balloon section. Thatminimum size can still be too large to enable the balloon to enter thelesion destined for treatment.

Moreover, the thrust recently has been toward making the in situ guidewire more, not less flexible in order to enable it more easily tonegotiate The tortuous path to the lesion. However, as the guide wirebecomes more flexible, its ability to inhibit The collapsing or foldingof the catheter tube diminishes.

Numerous attempts have been made over the years to design angioplastycatheters which are soft and flexible and yet can transmit axial forceswithout buckling. Among the most recent is reflected in U.S. Pat. No.4,616,653 (Samson) which discloses a combination angioplasty catheterwith a built-in guide wire. The system of the '653 patent employs a duallumen catheter, with the inner lumen beginning at the distal end of theballoon, passing through the balloon chamber and then the full length ofthe catheter tube, ending at its proximal end. In addition, the innerlumen of Samson has at least three segments, a small diameter segmentthat passes through the balloon chamber, a larger diameter segment thatpasses through the catheter tube and a transition segment between theother two.

While the device of the '653 patent may overcome some of the obstaclesof the prior art devices, it is believed to have its own drawbacks. Theuse of coaxial tubes over the entire length of the device addsunnecessary rigidity and reduced flexibility in regions where it may notbe needed or desired. Also, the use of a dual diameter inner tube, andthe need to provide a transition zone with a taper that will not stretchwhen the guide wire taper is forced into it is believed to make thedevice of the '653 patent unnecessarily difficult and costly tofabricate.

BRIEF DESCRIPTION OF THE PRESENT INVENTION

In accordance with one embodiment of the present invention, anangioplasty balloon catheter assembly is provided in which the guidewire, sometimes referred to merely as a safety guide, and the balloonare used in a cooperative relationship so that a force applied to theguide wire can advance the balloon through a restricted lesion area.This is accomplished by providing mechanical engagement between theguide wire and the balloon so that axial force applied to the wire fromoutside of the body of the patient will be transmitted to the distal endof the balloon. Further, in accordance with the invention, the distalend of the guide wire can be made highly flexible, or can be attached toa flexible coil spring, so that the guide wire can be more easilyadvanced through stenoses and accommodate sudden changes in direction.Also, most of the body of the catheter tube is of a single lumen design,thereby retaining the advantageous characteristics of such construction.

In one embodiment of the invention, the catheter tube runs from theextreme proximal end of the entire assembly to the proximal end of theballoon membrane, but preferably does not run through the balloonchamber to its distal end. In addition, a guide tube is provided. Theguide tube can include a neck extension on the distal end of theballoon. The guide tube continues from the tip end, into and through theballoon chamber, to and preferably slightly into the catheter tube,terminating in the distal portion of the catheter tube. The outsidediameter of the guide tube is smaller than the inside diameter of thecatheter tube.

The guide wire extends from, and preferably through the entire length ofthe guide tube and the balloon chamber as well as through the cathetertube and the fitting at the proximal end of the catheter tube. It isattached at the proximal end of the catheter tube to a rotating member,such as a knob, which preferably is incorporated as part of the proximalfitting. Stop means are associated with the guide wire to interact withthe proximal end of the guide tube. When force is applied to theproximal end of the guide wire, it will be transmitted along the lengthof the wire, to the guide tube and thence to the distal end of theballoon.

In another embodiment of the invention, the catheter tube is comprisedof an extension tube and a main body, which may be, for example, of thinwalled stainless steel tubing or a polyamide tube. The distal end of themain body forms a shoulder inside the extension tube and a coil springtransmits axial force from that shoulder to the guide tube. In thisembodiment, the axial force is transmitted primarily through thecatheter tube, rather than primarily through the guide wire.

Although it is believed that the catheter assembly structure of theinstant invention is particularly well suited for angioplasty ballooncatheters, it may also have utility for other types of catheters, forexample, intra-aortic balloon catheters.

Another feature of the instant invention is a catheter adaptor. Thisadaptor can be used with a variety of different types of catheters, butis believed particularly suited for use with PTCA catheters. The adaptorcan be removed and reattached, as need dictates. Also, the guide wirecan be removed with or without removal of the adaptor.

BRIEF DESCRIPTION OF THE DRAWINGS

Other objects and advantages of the present invention will become moreapparent upon reference to the following specification and annexeddrawings in which:

FIG. 1 is an extended schematic plan view of a preferred embodiment ofthe invention.

FIG. 2 is a cross sectional view of the distal end portion of theembodiment of FIG. 1;

FIG. 3 is a cross sectional view of the distal end portion of anotherembodiment of the invention:

FIG. 3A is a cross-sectional view of the distal end portion of a balloonangioplasty catheter

FIG. 4 is plan view of the proximal end of the catheter of an embodimentof the invention showing an adaptor and rotatable knob in cross section.

FIG. 5 is an enlarged cross sectional view of the forward compressionseal region of the adaptor of FIG. 4.

FIG. 6 is a side view of a split collet used in conjunction with theadaptor of FIG. 4.

FIG. 7 is a cross sectional view of an alternative embodiment of theadaptor of FIG. 4.

FIG. 8 is a cross sectional view of the distal end portion of a cathetershowing another embodiment of the instant invention.

FIG. 9 is a cross sectional view of the distal end portion of a cathetershowing yet another embodiment of the instant invention.

FIG. 10 is a cross sectional view of the distal end portion of acatheter showing still another embodiment of the instant invention.

FIG. 11 is also a cross sectional view of the distal end portion of acatheter showing yet one more embodiment of the instant invention.

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIG. 1, the angioplasty balloon catheter assembly 10 oneembodiment of the present invention includes a catheter tube 12, aballoon membrane 14, an adaptor or fitting 16 and a captive safety guide18. The proximal end of the catheter 12 fits into and is sealed toadaptor 16. Adaptor 16, which has a leg 24, is preferably molded ormachined of an inert, biologically compatible material.

Passing through the entire balloon catheter assembly is the safety guideor guide wire 18. At its proximal end, the guide wire is provided with arotatable knob 22 and at its distal end is a very flexible coil spring20.

Turning to FIG. 2, it can be seen that the proximal end 26 of balloonmembrane 14 is attached and sealed to the distal end of catheter 12 inconventional fashion, for example by gluing, chemical welding or thelike. The distal end 30 of balloon 14 is attached and sealed, again inconventional fashion, to the distal end portion of guide tube 28. At itsproximal end, guide tube 28 is attached to catheter tube 12, preferablyby a few or a series of circumferentially spaced spot welds 32. In thisembodiment, guide tube 28 acts not merely as a guide for the safetyguide wire, but as the support member for the balloon as well. Inaddition, in this embodiment, at least some axial force can betransmitted directly from the catheter tube to the guide tube and thenceto the distal end of the balloon.

Because guide tube 28 is attached to catheter Tube 12 and becauseballoon membrane 14 is attached to tube 28 at one end and to tube 12 atthe other, expansion of the membrane tends to stress the points ofattachment at both ends. Accordingly, if one wishes to avoid suchstresses, a cut 29 may be made in guide tube 28 to permit axial movementof its distal end relative to its proximal end, thereby preventing thedevelopment of stress at the points of attachment. Despite this cut,however, guide tube 28 acts as a support member for the balloon. Safetyguide 18 acts as a necessary support member only to bridge the gapcreated by cut 29. As another alternative, a spring can be employed tobridge this gap. It should be understood, however, that stress reliefmeans such as cut 29 are not necessary to practice the instantinvention.

As can be seen in FIGS. 3 and 8, the guide tube need not be attached tocatheter tube 12. Instead, it can float freely in the lumen of tube 12.When not so attached, there is even less need for stress relief cut 29(FIG. 8), although it still may be provided.

Also, the guide tube need not be made of solid wall tubing nor need itbe circular in cross section. All that is required is that a seal beestablished to prevent blood from entering the lumen of the catheterand/or the balloon chamber.

It is believed to be most desireable to provide for very closetolerances, perhaps on the order of 0.0005 inches, between the insidediameter of the guide tube and the outside diameter of guide wiresegment 36. Such close tolerances prevent seepage of blood into thecatheter tube and also prevent the balloon expansion fluid from escapinginto the blood stream. Under certain circumstances, however, additionalsealing means may be desireable. For example, the guide tube can befilled with a thixotropic material. Another method would be to employ anelastomeric seal 52 (FIG. 3).

It is believed most advantageous to provide for a tight fit betweenguide wire and guide tube over the entire length of the guide tube.Alternatively, a tight fit need only be assured over a portion of theguide tube's length. In the latter case, the structure and configurationof the remainder of the guide tube is largely a matter of choice.

As can also be seen in FIG. 2, the main body of safety guide 18 iscomprised of two segments, a proximal segment 34 and a distal segment36. Segment 34 is the longer of the two and has a larger diameter thanthat of segment 36. At its proximal end, segment 34 is attached to knob22 and at its distal end it is attached to segment 36. Segment 36 isattached at its proximal end to segment 34, and at its distal end it isattached to or formed into a coil 20.

Between its attachment to segment 34 and coal 20, segment 36 passesthrough guide tube 28. Accordingly, the inside diameter of guide tube 28must be larger than the diameter of segment 36. Obviously, thedimensions of these two cooperating elements may vary depending upon thesize of the balloon being employed. However, in a typical small diameteror predilatation catheter having an expanded balloon diameter of betweenabout 0.040 and about 0.160 inches, the guide tube might have an outsidediameter of about 0.010 inches and an inside diameter of 0.007 inches,whereas the safety guide segment 36 might have a diameter of 0.007inches and segment 34 might have a diameter of 0.013 inches.

The balloon portion of a predilatation catheter like that just referredto is generally about one inch long, with the catheter tube 12 having aninside diameter of about 0.024 inches and an outside diameter of about0.032 inches.

Because the two segments, 34 and 36, of guide wire 18 are of differingdiameters, a shoulder 38 is formed where they meet. The outside diameterof the shoulder is made larger than The inside diameter of guide tube28. Thus, when axial force is exerted on safety guide 18, face 38 of theshoulder abuts the proximal face 40 of guide tube 28 and therebytransmits the axial force to the guide tube, and through it, to thedistal end 30 of balloon 14.

Although in order to serve its mechanical support function in thisembodiment, the guide tube need be only so long as to prevent itsleaving the mouth of catheter 12 when balloon membrane is inflated, itmay be desireable, as is seen, for example, in FIGS. 3 and 8, to extendit slightly further into catheter 12 in order to improve the seal thatis created as a result of the close tolerances between the insidediameter of the guide tube and the outside diameter of the distalsegment of the guide wire. It is believed, however, that the guide tubeshould not extend into catheter 12 for a substantial portion of thelength of catheter 12. Most advantageously, the guide tube should notextend into catheter 12 for more than about 25% of the catheter'slength, and preferably not more than about 10% of its length.

While safety guide 18 effectively plugs the lumen of guide tube 28,because of the innovative structural arrangement at the proximal end oftube 28, fluid communication is maintained between the lumen of cathetertube 12 and the balloon chamber. Moreover, such communication ismaintained without employing a dual lumen catheter.

After exiting from the distal end of guide tube 28, safety guide segment36 may be attached to or may itself be formed into a coil 20. Theoutside diameter of coil 20 can be made larger than the inside diameterof guide tube 28, in which case axial movement of safety guide 18 wouldbe limited by shoulder face 38 in the distal direction and by coil 20 inthe proximal direction.

An alternative embodiment is depicted in FIG. 3. In this embodiment thetransition from proximal segment 54 to distal segment 56 of safety guide58 is by means of a frusto-conically shaped taper 55. This transitionsegment could take on a wide variety of other shapes, for example,frusto-spherical, frusto-elliptical or the like. When a taper is used, asleeve 53 may be used to prevent the taper from being jammed into theguide tube. Sleeve 53 would then also provide a bearing surface betweenthe taper and the guide tube. It will be readily apparent to thosefamiliar with this art that, as another alternative embodiment (FIG.3A), both the proximal segment 54 and the distal segment 56 of safetyguide 58 may be of the same diameter with a keeper or collar mountedthereon to act as the stop means.

Frequently a permanent bend is placed in the coil to enablethe:physician to "steer" it through a tortuous path and into the properone of numerous coronary arteries. Such "steering" is accomplished byrotation of knob 22.

As can be seen, for example in FIG. 2, the distance between the shoulderformed by face 38, and coil 20 is greater than the length of guide tube28. This is done so as to permit varying the distance by which coil 20leads the distal end 30 of the guide tube. Of course, the distancebetween coil 20 and the shoulder (or keeper, or taper, as the case maybe) can be the same as the length of guide tube 28. In that event,safety guide 18 would not be able to move axially relative to balloon14, but would still be able to rotate. As another alternative, if nocoil were to be used or if the coil were used but it were to be smallenough to fit through the guide tube, then there would be no restrictionon its movement in the proximal direction.

It is anticipated that in the most advantageous practice of the instantinvention, the diameter of the main body, or proximal segment of thesafety guide will be significantly larger than that of the distalsegment. During insertion and proper placement, the axial forcenecessary to advance the catheter assembly through the arterial tree andinto the stenosis of the lesion will be transmitted in part by thecatheter tube and in part by the safety guide. Since it is the proximalportion of the safety guide that will be carrying the safety guideportion of the load, the larger the diameter of that segment, thegreater the force it can transmit.

At the distal end, however, it is most advantageous to have the diameterof the safety guide as small as possible. The smaller the diameter ofthe distal segment, the smaller can be the diameter of the guide tuberunning through the balloon chamber and, consequently, the smaller canbe the entering profile of the collapsed balloon. When the safety guideis made to be captive, the diameter of its distal segment can be madesignificantly smaller than that of the smallest suitable indwellingsafety wire.

By use of a captive safety guide, a cooperative relationship isestablished between the safety guide and the catheter tube/guide tubeassembly. Reliance need not be placed on the guide wire alone tonegotiate the arterial tree and pass the region of the lesion.

Similarly, sole reliance need not be placed upon the catheter tube toaccomplish those tasks. Instead, each acts with and reinforces theother. In particular, since the rigidity of the assembly is greater thanthat of the safety guide alone, to achieve a given rigidity the diameterof the safety guide can be smaller than would be possible if the guidewire were of the indwelling type. This is especially important at thedistal end where a significantly smaller safety guide can be employedwithout compromising the ability to negotiate, steer and pass severerestrictions.

Due to the unique structure described herein, and particularly becauseprimary reliance is placed upon the guide tube for support of theballoon, the safety guide can be made free to rotate and/or to moveaxially without interfering with the ability of the balloon to be fedinto and through the arterial system or with its efficient functioningonce in place.

In order for safety guide 18 to transmit axial force from its proximalend to its distal end and thence to guide tube 28, knob 22 is provided.In addition, cooperating structure, as best seen in FIG. 5, is providedto permit the cooperative interaction referred to above. This structurepermits axial movement of the safety guide relative to fitting 16without interfering with the freedom of the safety guide to rotatewithin the fitting and within the catheter tube.

The adaptor 16 of FIG. 4 is removable from and reattachable to catheter12. Adaptor 16 has a forward compression cap 62 at its distal end, whichcompression cap has a hollow passage 64 therethrough with an internalthread 66 in the proximal end of passage 64. Adaptor 16 also has a Ybody midportion 68 with straight leg 70 and angled leg 72. Leg 70 hashollow passage 74 therethrough and leg 72 has hollow passage 76therethrough. Passage 76 communicates with passage 74, and passage 74communicates with passage 64. Passage 76 has an enlarged,frustoconically shaped proximal portion 78 designed to accept, influid-tight engagement, fluid pressure generating means, such as asyringe (not shown).

Leg 70 of body 68 has an external thread 80 at its distal end which isdesigned to engage thread 66 on compression cap 62.

Internally of cap 62 is compression seal 82. As best seen in FIG. 5,seal 82 has a hollow passage 84 therethrough and sloping convergingfaces 86 and 88. Compression cap 62 has an internal shoulder 90 of thesame slope as face 86 and Y body leg 70 terminates ay its distal end inan internal taper 92 having the same slope as face 88. Passage 84 isdesigned to accept catheter 12 therein.

When compression cap 62 is threaded tightly onto Y body 68, compressionseal 82 is squeezed between shoulder 90 and taper 92, which squeezing inturn forces the seal to expand inwardly against catheter tube 12 andproduces a fluid-tight seal between fitting 16 and tube 12. In order toprevent tube 12 from collapsing when seal 82 is compressed against it, asteel reinforcing sleeve 94 can be placed within its lumen.

The proximal end of Y body leg 70 terminates in an enlarged segment 96having an internal thread 106. A second compression seal 98 is placedwithin segment 96 between back-up plates 100 and 102. Seal 98 has ahollow passage therethrough designed to accept therein guide wire 18.

Proximal of leg 70 is compression knob 108 having a hollow passage 110therethrough, an enlarged segment 112 and a reduced diameter segment114. Segment 114 is provided with an external thread 116 designed toengage internal thread 106 at the proximal end of leg 70. Rotation ofknob 108 relative to Y body 68 compresses seal 98 between plates 102 and100 causing it to expand inwardly against guide wire 18 thereby forminga fluid-tight seal. However, since seal 98 is made of a deformableplastic and safety guide 18 is preferably stainless steel, a fluid-tightseal can be achieved without preventing rotation or axial movement ofthe safety guide within the seal.

Adaptor 16 is also provided with a torque handle 118 having hollowpassage 120 therethrough. The outside diameter of the distal segment 122of handle 118 is sized to fit slidably within passage 110. Proximal ofsegment 122 is rotating knob 124 having a diameter greater than that ofsegment 122 as well as of compression knob 108. The distal face 126 ofknob 124 acts as a stop or shoulder to limit axial travel in the distaldirection of handle 118 relative to compression knob 108.

The proximal end of handle 118 is provided with an external thread 128designed to engage the internal thread 130 on rear compression cap 132.There is also provided a metal split collet 134, having a sleeve portion136, a head portion 138, a hollow passage 140 therethrough sized toaccept safety guide 18 therein and a cut 142 running axially throughhead portion 134 and partially through sleeve portion 136. Sleeveportion 136 is sized to fit within the proximal end of the hollowpassage 120, but head portion 138 is too large to fit within thatcavity. Head portion 138 is provided with external converging faces 144and 146 designed to cooperate with similarly sloping internal faces onhandle 108 and on rear compression cap 132. Rotation of cap 132 relativeto handle 118 compresses head 138, thereby closing cut 142 until safetyguide 18 is gripped firmly within collet 134. Because the safety guideand the collet are both made of metal, this gripping action preventsboth rotational as well as axial movement between the two. Conversely,guide wire 18 can easily be adjusted simply by loosening cap 132. Inaddition, materials are selected for handle 118, cap 132 and collet 134which, upon threading cap 132 tightly onto handle 118, will preventrelative motion between those three elements.

In use, safety guide 18, which extends proximally of the end of tube 12,is passed through adaptor 16, while tube 12 is fed into forwardcompression cap 62 and through compression seal 82. Cap 62 is thanthreaded tightly onto Y body 68 to grab tube 12 and prevent its removal.Compression knob 108 is then threaded tightly into the proximal end of Ybody leg 70 to seal that end of leg 70 and prevent the escape of fluidtherefrom. Finally, rear compression cap 132 is tightened onto handle118 until guide wire 18 is held firmly therein.

When all three threaded engagements are tight, fluid pressure can beapplied through passage 76 of leg 72, through passage 74 to the lumen oftube 12 without preventing rotation and/or axial movement of handle 118relative to Y body 68. When it is desired to remove adaptor 16, thethree threads are loosened and the entire assembly can be removed fromthe catheter.

While adaptor 16 has been described for use in connection with anangioplasty catheter, its utility is not nearly so limited. It can beemployed with any catheter that might benefit from having adetachable/reattachable fitting. For example, it might be used at theproximal end of an intra-aortic balloon catheter.

The unique design of adaptor 16 offers the physician a degree offlexibility heretofore unheard of. For example, it permits removal ofthe guide wire from the catheter without removing the fitting. This canbe accomplished simply by unscrewing compression knob 108 from enlargedsegment 96 of leg 70 and loosening compression cap 132 so as to releasethe grip of collet 134. After the guide wire has been removed,compression knob 108 can be replaced by a solid cap (not shown).Screwing such a cap into enlarged segment 96 would maintain a fluidtight seal at the proximal end of the adaptor.

Similarly, by keeping compression knob 108 and compression cap 132 tightwhile loosening only compression cap 62, the adaptor and the guide wirecan be removed together, leaving only the catheter tube in place. Or, byloosening all three compression members, adaptor 16 can be removedwithout disturbing either the guide wire or the catheter tube.

As those skilled in the art will readily see, numerous variations on thebasic design of the adaptor can easily be made. For example, additionallegs similar to leg 72 could easily be provided. Another example of avariation is depicted in FIG. 7 which shows a detachable/reattachableadaptor 17 designed for use without a guide wire. As can be seen, in theembodiment of FIG. 7, straight leg 70 of FIG. 4 and all its associatedfittings and components have been eliminated. In addition, leg 72, whichin FIG. 4 was at an angle, is straight in FIG. 7.

In the embodiment of FIG. 7, the components having like numbers to thosein the FIGS. 4 and 5 embodiment function in the same manner as hasalready been described in connection with those other figures. Forexample, compression cap 62, compression seal 82, reinforcing sleeve 94and body 68 cooperate to hold and release catheter 12 in the FIG. 7configuration just as they do in the configuration of FIG. 4.

In another embodiment, depicted in FIG. 9, catheter 12 is necked down atits distal end 154. There is also provided a catheter extension tube152, the proximal end of which fits over the necked down portion 154 ofcatheter 12. Preferably, the outside diameter of extension 152 should besmaller than the outside diameter of the main body of catheter 12, and afluid tight seal should be established between the extension and thecatheter. This seal can be established by any conventional meanssuitable to the materials being employed. When adopting this embodiment,it is believed most advantageous that catheter 12 be of thin walledstainless steel tubing and extension 152 be of modified PET. However,other biocompatible materials may also be suitable.

In the embodiment of FIG. 9, guide tube 28 extends into catheterextension 152, but stops short of the distal end of catheter 12. Betweenthe proximal end of guide tube 28 and the distal end of catheter 12,there is provided a coil spring 150. As can be seen, the necked down endof catheter 12 forms a shoulder 156 inside catheter extension 152. Atits proximal end, spring 150 abuts this shoulder 156 and at its distalend spring 150 abuts the proximal end of guide tube 28. A cap 158 may beprovided over the proximal end of guide tube 28 to facilitate the evendistribution of force transmitted from spring 150 to tube 28 and toreinforce the end of tube 28.

A radiopaque marker 142 is provided on the embodiments of FIGS. 8 and 9and can be used by the physician viewing the procedure under fluoroscopyto determine where the balloon membrane begins. Similar radiopaquemarkers would probably be desireable on any of the embodiments of theinstant invention. Practice of this invention, however, does not dependupon the use of radiopaque markers.

Although it is believed preferable to have an extended guide tube toinsure a proper seal, it may also be possible for the guide tube to beshort, as is depicted at 158 in FIGS. 10 and 11. In these figures thecatheter 12 extends to the proximal end of balloon 14 similar to thestructure depicted in FIGS. 2 and 3. In FIG. 10, however, axial force istransmitted to guide tube 158 through spring 160, whereas in FIG. 11wire 162 serves this purpose.

In using the device of the instant invention, access to the lumen of asuitable artery, usually the femoral artery, is achieved in conventionalfashion. The balloon catheter is then inserted into the artery and fedthrough the arterial tree, again, all in conventional fashion.Initially, and until an obstruction is reached, the balloon can beadvanced simply by pushing on the catheter tube.

As the physician exerts axial force on catheter 12, in the embodimentsof FIGS. 2 and 3, that axial force is transferred to the safety guide 18through fitting 16. Because of the close fit between distal segment 36of guide wire 18 and guide tube 28, friction will cause the transfer ofthat axial force to the guide tube and thence to the distal end of theballoon membrane. In the embodiment of FIG. 8, these frictional forcesmay be assisted or even supplanted by the transfer of force fromcatheter tube 12 through coil spring 150 to the proximal end of guidetube 28. In this embodiment, since reliance is not placed upon The guidewire to transmit axial force, the guide wire can be dispensed with.Alternatively, it can be made removable. As another alternative, thecatheter could readily be adapted to pass over an indwelling guide wire.

When an obstruction is encountered, either due to tortuosity or stenosisor otherwise, rotating knob 22 can be used to steer the distal tip ofguide wire 18 around it. Also, axial force can be applied to knob 22 tofacilitate feeding of the balloon past the obstruction. Feeding of theballoon through the arterial system can continue by pushing on tube 12and/or on fitting 16 simultaneously, thereby causing the transmission ofaxial forces to be shared by the catheter tube and the safety guide.

Under certain circumstances, for example, severe tortuosity or stenosis,friction alone may not be sufficient to overcome the resistanceencountered. In that case, the guide tube will begin to slide axially inthe proximal direction relative to catheter 12 until it encountersshoulder 38 (in the embodiment of FIG. 2) or taper 55 (of the embodimentof FIGS. 3 and 8). Alternatively, means could be provided anywhere alongdistal segment 36 to prevent or restrict axial movement of that segmentrelative to the guide tube. For example, a retaining ring (not shown)could be affixed to segment 36 and a cooperating annular cut-outprovided on the inside of guide tube 28. If the length of the annularcut-out were greater than the thickness of the retaining ring, therewould be leeway for a limited amount of relative axial movement. If thetwo were about the same size, substantially no relative motion couldoccur.

Although it is believed that the most advantageous means for practicingthe subject invention is to employ a single adaptor, that is not anecessary attribute. The safety guide can be made to exit the cathetertube before the latter enters the adaptor. In that event, a secondadaptor would be provided solely for the safety guide, with the firstadaptor acting merely as the interface for connecting the catheter tubeto the source of fluid pressure.

It is believed apparent from the foregoing that in the instant inventionthere is provided a significant step forward in the design of PTCAcatheters. As will be equally apparent, the description set out aboveand the embodiments disclosed are necessarily only illustrative.Numerous changes, modifications and variations will readily occur tothose familiar with this art and as such they should be deemed to fallwithin the broad scope of this invention as that scope is defined in thefollowing claims.

I claim:
 1. A balloon catheter assembly comprising:a catheter tube having a main body portion and a distal portion terminating respectively in proximal and distal ends and having an inflation lumen therein, a balloon membrane having proximal and distal ends, wherein its proximal end is attached to the distal portion of said catheter tube, a guide tube having proximal and distal portions terminating respectively in proximal and distal ends and a lumen therein, wherein the distal end of said membrane is attached to said guide tube, a balloon chamber defined by said membrane and its attachment at one end to said catheter tube and at its other end to said guide tube wherein said chamber is in communication with the lumen of said catheter tube and wherein, when not inflated, said balloon chamber extends distally of the distal end of said catheter tube, a captive guidewire having an axially elongated proximal portion disposed within the inflation lumen of said catheter tube and having an axially elongated distal portion disposed through the lumen of said guide tube and extending distally thereof, and a resilient spring member coupled between said catheter tube and said guide tube for transmitting axial force from said catheter tube to said guide tube, while permitting fluid communication between the inflation lumen of said catheter tube and said balloon membrane.
 2. The catheter of claim 1 wherein said guide tube extends into the inflation lumen of said catheter tube.
 3. The catheter of claim 2 wherein said guide tube extends into the inflation lumen of said catheter tube less than a major portion of the length of said catheter tube.
 4. The catheter of claim 1 wherein said spring member comprises an open coil spring disposed between the distal portion of said catheter tube and the proximal portion of said guide tube.
 5. The catheter of claim 4 wherein said coil spring is disposed about a portion of said captive guidewire.
 6. The catheter of claim 1 wherein said spring member comprises a resilient wire member disposed between the distal portion of said catheter tube and the proximal portion of said guide tube.
 7. The catheter of claim 1 wherein the distal portion of said catheter tube comprises an extension tube made of a different material than the main body portion of said catheter tube.
 8. The catheter of claim 7 wherein the proximal portion of said catheter tube comprises stainless steel and said extension tube comprises biologically compatible plastic.
 9. The catheter of claim 8 wherein said extension tube comprises PET.
 10. The catheter of claim 1 further comprising shoulder means between said main body portion and the distal portion of said catheter tube, wherein said resilient spring member is coupled between said shoulder means and said guide tube.
 11. The catheter of claim 1 wherein the diameter of the proximal portion of said captive guidewire is larger than the diameter of the lumen of said guide tube.
 12. The catheter of claim 1 wherein said guidewire comprises a transition segment between the proximal and distal portions of said guidewire, and wherein a portion of said transition segment can pass into the guidewire lumen of said guide tube.
 13. The catheter of claim 12 wherein said transition segment is frusto-conically shaped.
 14. (Amended) The catheter of claim 12 further comprising a sleeve on the distal portion of said guidewire for preventing said transition segment from becoming jammed into the lumen of said guide tube.
 15. The catheter of claim 12 wherein said transition segment is frusto-spherically shaped.
 16. The catheter of claim 12 wherein said transition segment is frusto-elliptically shaped.
 17. The catheter of claim 1 further comprising a collar mounted on said guidewire proximally of said guide tube, said collar serving as a stop means.
 18. The catheter of claim 1 further comprising a coil member on the distal end of said guidewire, said coil having an outer diameter larger than the diameter of the lumen of said guide tube.
 19. The catheter of claim 18 wherein said coil member has a bent portion that extends along an axis that intersects the axis of the distal portion of said captive guidewire.
 20. The catheter of claim 1 further comprising a cap disposed over the proximal end of said guide tube, whereby said cap facilitates the even distribution of force transmitted from said resilient spring member to said guide tube.
 21. The catheter of claim 1 wherein the distal portion of said guidewire extends through the guidewire lumen of said guide tube in a manner characterized in that resistance to fluid flow inside the lumen of said guide tube is substantially greater than resistance to fluid flow between the lumen of said catheter tube and said balloon membrane.
 22. The catheter of claim 21 further comprising a sealing means between said guide tube and said guidewire, whereby a substantially fluid-tight seal is created.
 23. The catheter of claim 22 wherein said sealing means comprises an elastomeric seal.
 24. The catheter of claim 1 wherein said guide tube has length shorter than the length of said balloon membrane.
 25. A balloon dilatation catheter for performing angioplasty procedures within a patient's arterial system comprising:a) an elongated catheter body having an inner tubular member with a first inner lumen extending therethrough and a distal end with a port in fluid communication with the first inner lumen both of which are adapted to receive a rotatable guidewire therein, and a hollow outer tubular member which is disposed about the inner tubular member and which has a section in a distal part of the catheter body with a limited portion of the inner periphery thereof bonded by bonding material directly to the exterior of the inner tubular member, the unbonded portion of the section of the hollow outer tubular member defining a second inner lumen between the inner and outer tubular members; b) a captive guidewire disposed through said hollow outer tubular member and through said first inner lumen of said inner tube; c) an inflatable dilatation balloon, located distal to the bonded section of the outer tubular member, having an interior in fluid communication with the second inner lumen, having a proximal end attached to the distal portion of said outer tubular member, and having a distal end attached to the distal portion of the inner tubular member, which extends through the interior of the balloon; d) means to direct inflation fluid from a source through the second inner lumen to the interior of the balloon; and e) means for relieving stress at locations of attachment between the proximal and distal ends of said balloon and the distal portions of said outer and inner tubular members, respectively.
 26. The catheter of claim 25 wherein said stress-relieving means comprises a gap separating said inner tubular member into two segments.
 27. The catheter of claim 26 wherein said guidewire extends through the first inner lumen of said inner tubular member in a manner characterized in that the resistance to fluid flow inside the lumen of said inner tubular member is substantially greater than resistance to fluid flow between the second inner lumen and said balloon. 